Catalytic isomerization of olefinic hydrocarbons



Patented Apr. 2, I

oAraLmc rsomani'za'non or oLEFnuc g nrnaocsnaons Lloyd Berg, O'Hara Township, Allegheny County, and George Lewis Sumner, Jr., and Charles W.

Montgomery, Oakmont, Pa asoignors to Guli Research a: Development Company, Pittsburg Pa a corporation of Delaware No Drawing." Application August 21, 1945. 4': 1

7 Serial No. 611,918

13 Claims. (CL 2604833) This invention relates to the catalytic isomeriz'ation oi oleflnic hydrocarbons and more particularly to a process for the catalyticisomerization of olefin-containing gasoline toincrease its anti-knock rating;

The process is particularly applicable to gasolines or naphthas containing an appreciable quantity of oleiins, such as gasoline obtained by thermal. cracking. Thermally cracked gasolines have an averagejoctane rating considerably below that or the thermodynamic equilibrium value and a process tending towards the establishment of this equilibrium will be characterized by a consider- 4 able octane improvement.

In catalytic cracking the catalyst tends to produce some olefin isomeriz ation and hence catalytieally cracked gasolines have already been isomerized to some extent and thus do not show the improvement in octane number that is shown with thermally cracked gasolines when subjected .to isomerization conditions. In addition, the

lower the original octane rating of the charge the greater will be the increase upon isomerization.

Theprocess oi isomerization is particularly applicable to'charge stocks characterized by a high olefin content, especially olefins of the nonbranched type. Thermally cracked distillates and coke still gasolines are especially adaptable to this process, while oleflnic polyiorm stocks, that is, gasolines cracked in the presence of light 1137- drocarbon gases, are not so improved by the process as the other charge stocks.

It is desirable to carry out the isomerization reaction alone while holding other reactions such as cracking, saturation, aromatization, treating and hydrogen transfer to a minimum. In the prior art processes of isomerization these other reactions have not been suillciently suppressed. The catalysts and conditions described in these processes are of such a nature as to bring about side reactions. Also. those of the prior art processes which have been directed to gasolines have usually been concerned with improving the octane number from 55-60 to 65-68, while it is most desirable to increase thermally cracked stocks alfrom 0 to 200 pounds per square inch. mum-results are obtained in the preferable range of 375-425 C., 0.3-1.3 space velocity and atmospheric pressure. j

The process is characterized by liquid yields in excess of 95 per cent and usually 97-99 per cent. The reaction is almost entirely one of iso merization since there is very little cracking, saturation, aromatization, treating and hydrogen transfer. Octane numbers of thermally crackedstocks are increased substantially even with the higher octane rating charge stocks.

Further, the octane ratingsbi the leaded gasolines are correspondingly increased so that ,an

isomerized leaded sample hasa rating several units higher than an unisomerized sample contalning the same amount of lead. Therefore, the

process is not merely a substitute for tetraethyl lead but permits the reaching, with the stockscontemplated, of octane numbers impossibleto obtain by leading alone.

' The catalyst of the present invention is alumina which is maintained at a proper degree of activation by treating the alumina with anhydrous'hydrogen chloride. The catalyst may be prep red as follows: 800 parts 01 alumina pellets ready having an octane number of 65-68 and upgrading them to '71-'12.

The process of the present invention comprises passing the charging stock over a catalyst of alumina impregnated with anhydrous hydrogen chloride. The reaction conditions include a temperature range of from 300-600 C. and a space velocity of from 0.1 to 20 volumes of hydrocarbon per hour per volume of catalyst and pressures were dried at 250. C. and after coolingto room temperature, anhydrous hydrogen chloride was passed through the pellets for two hours. Heat was applied and the anhydrous hydrogen chloride passed through for another. hour at which time the temperature was allowed to reach 400 C.

The catalyst was then purged with nitrogen gas for about 15 minutes. The catalyst contained about 4.0 volumes of hydrogen chloride per volume of catalyst.

As the catalyst is usable deposit of carbonaceous material is laid down upon the catalyst suriace. reducing its activity and necessitatin periodic burn-oils. Burning-of! can be accomplished with air, maintainingthe burn-oil. temperature below the sintering temperature of the catalyst, about 1100 F. The catalyst will gradually lose activity if it islnot periodically reactivated. Activation is. accomplished by passing 1 to 20 volumes of anhydrous hydrogen chloride per volume otcatalyst over the catalyst at room temperature and then gradually raising the temperature to that oithe reaction. After the excess hydrogen chloride has been swept out with an inert gas, the hydrocarbon feed is passed over thecatalyst. The physical shape of the alumina appears to have little efiect upon the catalytic activity, equally successful results having been obtained with Y inch pellets and with 8-14 mesh granules.

Opti- Table I summarizes data showing the gradual decrease of the catalyst activity when not periodically reactivated. 'Runs 1, 2 and 3 show the gradual decrease inoctane improvement when thecatalyst is burned, oil but not reactivated.

anhydrous hydrogen chloride. I

Table I Run No l Throughput, vols. gasoline/vol. catalyst 0. 2 as 9. 2 '9. 5 Cycle No 1 2 3 4 Temperature, C. 400 400 400 Space velocity, hr: 0. 5 0. 5 0. 5 Catalyst Octane number increase:

A. T. M. motor method, D35743T 2.4 2.3 1.5 2.6 A. S. T. M.motor,method, +1 cc. T. E. L. 4. 2 3. 6 3. 1 4. 0 A. S. T. M. motor method, +3 cc. T. E. L. 3. l 2. 8 2. 0 2. 9

Alumina-HCI I Alumina The length of the cycle between carbon burnoifs may be 10-30 volumes-of charge per volume of catalyst, with very little sacrifice'in octane improvement at -20 vol./vol. catalyst. activation need not accompany each carbon bumon. This small carbon deposit indicates very little side reaction such as cracking or dehydrogenation.

The use of anhydrous hydrogen chloride invariably introduces a quantity of chlorine in the treated distillatewhich has a detrimental eflect upon the lead susceptibility of the product. The isomerized product should be passed over a substance which will remove the chlorine withoutotherwise affecting the product. Bauxite at ZOO-500 C. and

the alumina catalyst activated with.

The rearomatics 9 per cent,'paraflins and naphthenes 49.

per cent, the bromine'number was 58,. average molecular weight was 107.

Example 2.Thirteen volumes of gasoline were and the 7 passed over one volume of Va inch'alumina pellets activated with anhydrous hydrogen chloride at a temperature Of' 400 C. and 0.5 vol/vol. hour space velocity. The resulting product was dehalogenated over bauxite at 280 C. and deeblorized over clay at 250 C. The following A. SFT.

motor method octane numbers were obtained on the blended 10 pound Reid vapor pressure gaso- After the run was completed, the catalyst was swept free of hydrocarbon gases with nitrogen. With the catalyst still at approximately 400 C.. a slow stream or air was passed through the catalyst bed. The temperature of the catalyst at the 'air entrance rose to about 560 C. at which temperature the incoming air was shut oil. I The catalyst was allowed to cool to 500 C.- and the process repeated. The high temperature regeneration zone worked its way gradually through the catalyst bed. After this zone had-passed completely through the catalyst bed, addition of air only tended to cool the catalyst and no more carbon dioxide could be detected in the emuent gases.

Reactivation was accomplished by passing one to twenty volumes of anhydroushydrogen chloof removal of chlorine. All the results reported herein are for such dehalogenated products.

Example 1.-'-The ability of this catalyst to effect isomerization with the almostcomplete exclu sion of any other side reaction is best shown bythe treatment '01 n-octene-l. .Three volumes of n-octene-l were passed over one volume of A;

-inchalumina pelietsactivated with anhydrous hydrogen chloride at a temperature of 400 C. and 0.5 vol/vol. hour space velocity. The resulting product was dehalogenated over bauxite at 280 C. and decolorized over clay at 250 C. The

following data were obtained on the charge and the product:

I The i'ollowing examples show the use of this catalyst for gasolines. The charge stock in Examples 2. 3 and 4 was a debutanized thermally Inspection Charge Product Change Per cent olefin 95.9 91. 9 -4. 0 Per centperaflin and naphthene.... 4. l 8. 1 +4. 0 Octane numbers: r

A. S. T. M. motor method..... 36.7 74.9 +38.2 A. S. T. M. otor method 3 00. T. E. L, 60. 2 82.6 e +22. 4

- sintered.

ride per volume of catalyst overthe catalyst at 20-400 C. and over a period of one to six hours. In this case, ten volumes of anhydrous hydrogen chloride i were used. taking three hours time.

Aftertwo hours at room temperature, the temperature was raised to 400 C. during the third hour. At the end of that time, the excess hydrogen chloride was swept'out with nitrogenand the isomerization of the charge stock begun.

Examplle 3.Ten volumes of gasoline charge were passed over alumina granules of 8-44 mesh activated with anhydrous hydrogen'chloride at the same conditions as Example l. The 'following results were noted on the-10-lb. Reid vapor pressure gascllnes:

. )7 Improve- Charge Product mam A. s. 'r. M. motor method e1. 5 11.4 A.TS.I'cl.LM. motor method 1 cc. 7 4 3 +3 9 s 77.9 r A. S. '1. M. motor method 3 cc. o T. E. L 3..---- 7s. 7 sa s +3. 0

The life of the catalyst was found to be satisfactory provided that the burn-off is controlled so that the catalyst is thoroughly cleaned yet not Example 4.-Two hundred and sixty-five volumes of gasoline charge were passed over one volume of V8 inch alumina pelletsaunder conditions comparable with the preceding examples. The catalyst was burned oil and reactivated twenty-three times during the run. The length of each cycle between burw-ofis was varied from nine to twenty-two volumes or charge per volume of catalyst. The following octane improvements were obtained? Improvement Qharge- Product A. S. T. M. motor method A. B. T. M. motor method 1 cc. '1. E. L

A. 8.1. M.motor method 3 cc.

a1. s-oa o There was no decline in catalyst latter cycles. I

A. S. T.'M. distillation range 110-402 E, a bromine number of 35. and a hydrocarbon analysis or oleflns 31 per cent, aromatics 23 per cent, and paramns and naphthenes 46 per cent, and an averagemolecular weight of 137 was. obtained by the rectification oi the heavy bottoms obtained in the pressure tar separator from 'a thermal cracking plant. passed over the V8 inch alumina pellets activated with anhydrous hydrogen chloride. At a temperature of 400 C., atmospheric pressure and a space velocity of 0.5 hr.- the following octane rating changes were obtained:

Nine volumes ot'this gasoline were aeeaesa Zztivity in th- Example 5.-A gasoline having Example 6.-A series of runs were made on a debutanlzed polyform gasoline, having an A. S. 'I. M. distillation range 9i430 F., a

, bromine number of 40.5, a hydrocarbon analysis 01' oleflns 28.4 per cent, aromatics 16.8 per cent, and parafilnsand naphthenes'54.8 per cent, and an average molecular weight of 109, using alumina granules of 8-14 mesh activated with anhydrous hydrogen chloride as catalyst. At, 400 C., atmospheric pressure, and 0.5 hr:- space velocity, the following results were obtained:

Run No.

Octane No. increase: a v A. S. 'I. M. motor method 2. 2 2. 3 2. 3 2. 3 A. S. T. M. motor method 3 cc. T. E.'L 2.1 1. 0 2. 0 2. 6

The octane rating of this charge stock was:

A. S. T. M. motor method=72.5 A. S. T.- M. motor method-+3 cc. T. E. L.=82.'7

In the examples cited above the hydrocarbon analysis and the bromine numbershowed very little change, under proper conditions less than 10 per cent of their original value, giving adequate proof that the improvements obtained are the result of the isomerization of the olefins.

It will be understood that the'catalyst of the present invention is alumina activated by anhydrous hydrogen chloride and not aluminum chloride, since no measurable amount of aluminum chloride is formed by reaction.

Thus we have described a new and useful invention for the isomerization of olefin hydrocarbons, particularly in thermally cracked gasolines, for the improvement of octane number therein, by passing the charge over a catalyst comprising alumina which has been impregnated with anhydrous hydrogen chloride. The resulting isomerization and increased octane number are the only substantial changes in the gasoline and there is no measurable cracking, saturatiom;

aromatization, treating or hydrogen transfer.

. What we claim is:

1. A method for isomerizing olefin hydrocarbons which comprises passing said hydrocarbons at a temperature of from 300 to600 C. over a catalyst comprising alumina impregnated with anhydrous hydrogen chloride.

2. A method for increasing the octane num- 'ber of thermally cracked gasoline comprising passing said gasoline at a temperature of from 300 to 600 C. over a catalyst comprising alumina impregnated with anhydrous hydrogen chloride.

3. A method for isomerizing olefin hydrocarbons which comprises passing said hydrocarbons at a temperature of from 300 to 600 C. over a catalyst comprising alumina impregnated with anhydrous hydrogen chloride, at a space velocity of from 0.1to 20 volumes of said hydrocarbon per hour per volume of catalyst.

4. A method for isomerizing olefin hydrocarbons which comprises passing said hydrocarbons at a temperature of from 300 to 600 C. over a catalyst comprising alumina impregnated with anhydrous hydrogen chloride at a space velocity of from 0.1 to 20 volumes of said hydrocarbon per hour per volume of catalyst at a pressure not in excess of 200pounds per square inch.

5. A method for increasing the octane number of thermally cracked gasoline comprising passing said gasoline at a temperature of from 375 to 425 C. over a. catalyst comprising alumina impregnated with anhydrous lhydrogen chloride. 6. A method for increasing the octane num+ ber of thermally cracked gasoline comprising passing said gasoline at a. temperatureof from 375 to 425 C. over a catalyst comprising alumina, impregnated with anhydrous hydrogen chloride at a space velocity of from 0.3 to 1.3

volumes of gasoline per hour per volume of catalyst and at substantially atmospheric pressure. 7. A method for increasing the octane number of thermally cracked gasoline comprising passing said gasoline at a temperature of from 300 to600 C. over a catalyst comprising alumina impregnated with about 4 volumes of anhydrous hydrogen chloride per volume of alumina.

8. Amethod for increasing the octane number of thermally cracked gasoline comprising passing said gasoline over a catalyst comprising ,alumina which has been dried and impregnated with anhydrous hydrogen chloride for several hours at a temperature of from room temperature to 400 C.

9. A method for increasingthe octane number of thermally cracked gasolinecomprising passing said gasoline at 'a' temperature of from 300 to 600 C. over a catalyst comprising alumina impregnated with anhydrous hydrogen chloride, interrupting the passage of gasoline periodically and passing oxygen over the catalyst to remove carbon deposited thereon.

10. A method for increasing the octane number of thermally cracked gasoline comprising passing said gasoline at a temperature of from 300 to 600 C. over a catalyst comprising alumina impregnated with-anhydrous hydrogen chloride, interrupting the passage of gasoline periodically, passing oxygen over the catalyst,

subsequently passing anhydrous hydrogen chloof anoleflnic gasoline comprising isomerizing the olefins by passing said gasoline at a temperature "of from' 300 to 600 C. over a catalyst comprisingalumina impregnated with anhydrous hydrogen chloride and leaving the other constituents substantially unafiected.

12. A method for increasing the octane number of thermally cracked gasoline comprising passing said gasoline at a temperature of from 300 to 600 C. over a catalyst comprisin alumina impregnated with anhydrous hydrogen rine from said gasoline.

13. A method for increasing the octane num- "ber of thermally cracked gasoline comprising passing said gasoline at a temperature of from ,300 to 600- C. over a catalyst comprising alumina impregnated with anhydrous hydrogen chloride and subsequently removing any chlorine i0 bauxite per hour.

LLOYD BERG.

GEORGE LEWIS SUMNER, JR. CHARLES W. MONTGONIERY. 

